Corrosion inhibitor

ABSTRACT

A food grade corrosion inhibitor for admixture with a food-grade petroleum-based oil is derived from an admixture of food-grade components. The corrosion inhibitor, a food-grade isoalkane, a food-grade ester and imidazoline. The additive is incorporated into a lubricating component such as mineral oil, etc.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns corrosion inhibitors. More particularly,the present invention relates to corrosion inhibitors for use withlubricants. Even more particularly, the present invention concerns foodgrade corrosion inhibitors for use with lubricants and lubricantsprepared therefrom. 2. Description of the Prior Art

As is known to those skilled in the art, lubricants are used inpractically every environment where two parts undesirably mesh or rubtogether to create friction. Thus, every conceivable type of machineryincluding, for example, vehicles, factory equipment, agriculturalequipment, simple mechanical devices, such a lawn mowers, etc. allemploy lubricants of some sort to minimize the wear and tear and toreduce friction.

While each type of lubricant is selected according to the environment inwhich it is employed, petroleum-based oil compositions are the mostpopular and widely employed lubricants. Other lubricant compositions arethe soap-type lubricants prepared from organic fatty acids, as well ssynthetic lubricant compositions based upon diamines, silicones, etc.

For example, within the food processing industry, lubricants areemployed for maintaining lubricity between conveyors and the containerspassing therealong. Likewise, food-handling equipment such as fillers,sprayers, etc. also employ lubricants. It is to be appreciated thatbecause of the environment in which the lubricants are employed it isessential that the lubricant not contaminate the comestible which isbeing processed at the location. Such contamination creates obviousdifficulties and potential hazards. Thus, great care must be taken notonly in lubricant selection, but lubricant use as well.

Alternatively, in machining plants lubricants must be used forconveyors, transmissions, etc. Although contamination may not be aproblem, it is essential to the composition or formulation of a goodlubricant that a corrosion inhibitor be incorporated therewith. Just asbacteriostatic compounds, buffers, etc. must be incorporated into suchformulations, necessarily, because of the environments in which thelubricants are employed, it is essential that corrosion inhibitors beincorporated therewith in order to enhance the efficacy of thelubricant.

It is to be appreciated, again, that in a food processing environment itwould be most advantageous to employ a food-grade corrosion inhibitorwhich can be easily admixed and incorporated into the lubricant tothereby further reduce the hazards attendant the use of such lubricant.Furthermore, it is to be appreciated that a food-grade corrosioninhibitor also reduces the risk of using lubricants where the potentialfor ingestion of the lubricant, whether by accident or otherwise, is afactor.

In. U.S. Pat. No. 5,614,479, the disclosure of which is herebyincorporated by reference, there is disclosed a previously acknowledgedfood grade or GRAS (Generally Regarded as Safe) corrosion inhibitorwhich incorporates a ketone as an essential component. However, becauseof the odor of the inhibitor, attributable to the ketone, this lubricantis no longer deemed food grade.

Thus, the present invention, as will be subsequently detailed, providesa corrosion inhibitor comprising an admixture of components which isdeemed food grade or GRAS, as defined by present Federal regulations.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a corrosioninhibitor comprising an admixture of:

(a) a food-grade ester;

(b) an alkane or paraffin; and

(c) an imidazoline.

The components hereof are, as noted, food grade or GRAS components. Bythe term “food-grade” or GRAS is meant those compounds which have beendenoted by the Federal Government and, in particular, the Food and DrugAdministration, as being acceptable in foodstuffs or which can be usedin environments which come into contact with foodstuffs.

The food-grade esters can comprise a single ester or mixtures thereof.

Likewise, the paraffinic compound or alkane is, preferably, an isoalkanecan, also, comprise a mixture thereof.

The composition hereof can be admixed with a suitable lubricantcomposition. Preferably, it is admixed with a food-grade petroleumdistillate lubricant composition, such as mineral oil or the like.

For a more complete understanding of the present invention, reference ismade to the following detailed description and accompanying illustrativeexamples.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As noted above, and in accordance with the present invention, there isprovided a food-grade corrosion inhibitor for use with lubricationcompositions or lubricants, as well as the resulting lubricantcomposition.

The corrosion inhibitor hereof generally comprises an admixture of:

(a) a food-grade ester;

(b) a food-grade alkane; and

(c) an imidazoline.

The corrosion inhibitor comprises an admixture of the components whichcan be blended with a suitable lubricant, such as a petroleum-basedlubricant, preferably mineral oil, to form the use lubricant hereof.

The alkane which is used herein is either linear or branched and ispreferably a liquid, unsubstituted branched alkane (isoalkane) orisoparaffin, i.e., an isoalkane having from about six to about twentycarbon atoms and mixtures thereof.

In practicing the present invention a preferred class of isoalkanes arethose sold commercially by Exxon Mobil under the name ISOPAR. Aparticularly preferred isoalkane is that sold under the name ISOPAR G.Isopar G is described as a clear, odorless petroleum distillate. Otheruseful isoalkanes include those sold under the names ISOPAR H, L and/orM. Mixtures of these isoalkanes can be used.

In use, the isoalkane is present in an amount ranging from about 70% toabout 95%, by volume of the additive, based upon the total volume of theadditive and, preferably, from about 75% to about 90%, by volume, basedon the total volume thereof.

The food grade ester is traditionally denoted as one derived from afatty acid. The fatty acid esters utilized herein generally correspondto the formula:

R—C—R′

wherein R′ is a hydrocarbon radical having from about 12 to about 20carbon atoms in the alkyl portion thereof. R′ is, preferably, a loweralkyl such as methyl, ethyl, propyl or the like.

Amongst the useful higher fatty acid-based esters are, for example,oleates, palmitates, laureates, linoleates, and the like as well asmixtures thereof.

In practicing the present invention, the ester is present in an amountranging from about 5% to about 15%, by volume, based upon the totalvolume of the additive and, preferably, is present in an amount rangingfrom about 10% to about 15% by volume, based on the total volume of theadditive.

In practicing the present invention it is advantageous that the organicportion of the ester and that of the isoalkane alkane be the same. Inother words, when the isoalkane is palmitate, it is highly desirable,although not essential, that R likewise be palmitate.

The imidazoline is present in an amount ranging from about 1% to about10%, by volume, based upon the total volume of the corrosion inhibitingadditive and is, preferably, present in an amount ranging from about 5%to about 10%, by volume, based upon the total weight of the additive.

The additive, itself, is prepared by admixing the components togetherunder ambient conditions.

In use, the corrosion inhibitor hereof is preferably admixed with anysuitable petroleum-based lubricant. Generally, the corrosion inhibitorhereof comprises from about 1% to about 20%, by volume, based on thetotal weight of the lubricant composition.

Preferably, the petroleum-based lubricant is mineral oil. The mineraloil defines a transport medium into which the additive can be readilyadded and admixed therewith. Since the other components are organic innature, the components are readily admixed with the mineral oil withoutseparation or suspension. The term “mineral oil” as used herein definesa refined hydrocarbon oil without animal or vegetable additives. Mineraloil, as such, is a widely known and commercially available product. Aparticularly preferred refined grade of mineral oil which is denoted asmineral oil is “white oil.”

In practicing the present invention, generally, the white oil, comprisesfrom about 80 to 99%, by weight, of the total volume hereof. Preferably,the white oil is present in an amount ranging from about 85% to about95% by volume, based upon the total volume of the composition.

In this regard, other food-grade lubricants, such as glycerine orglycerol, coconut oil, etc. and the like, as well as mixtures thereof,may be used herein either alone or in admixture with the white oil.However, the white oil is preferred.

The additive hereof is admixed with the lubricant by any conventionalmeans at ambient conditions.

The composition hereof is solvent neutral and may be used in any of awide variety of environments. In addition to its utility as a lubricant,the composition also functions as a functional fluid, such as anautomatic transmission fluid, brake fluid or the like.

For a more complete understanding of the present invention, reference ismade to the following examples. In the examples, which are to beconstrued as illustrative rather than limitative of the presentinvention, all parts are by volume absent indications to the contrary.

EXAMPLE I

This example illustrates the preparation of a corrosion inhibitoradditive in accordance with the present invention. Into a suitablevessel equipped with stirring means is added the following at roomtemperature:

Ingredient Amount, pbv ISOPAR G 4.0 Methyl laureate 1.0 Imidazoline 0.5

The above corrosion inhibitor composition is then admixed with 94.5parts of white oil at ambient conditions. The resulting composition isuseful as a transmission fluid.

EXAMPLE II

This example illustrates the preparation of a lubricant composition inaccordance herewith.

Into a suitable vessel equipped with a suitable stirrer is charged aquantity of white oil. To the white oil is added, serially, food gradecorrosion inhibiting components to form a lubricant.

The following sets forth the components and the amounts thereof.

Ingredient Amount, pbv White oil 90.00 ISOPAR G 8.00 Methyl laurate 1.00Imidazoline 1.0

Having thus described the invention, what is claimed is:
 1. A food-gradecorrosion inhibitor for use in a lubricant composition, comprising: (a)from about 70% to about 90%, by volume, based on the total weight of theinhibitor, of a food-grade isoalkane; (b) from about 5% to about 15%, byvolume, based on the total volume of the inhibitor, of a food-gradeester; and (c) from about 1% to about 10%, by volume, based on the totalvolume of the inhibitor, of imidazoline.
 2. The corrosion inhibitor ofclaim 1 wherein the ester corresponds to the formula:R—C—OR′, wherein R is a hydrocarbon radical, saturated or unsaturatedR′, having from about C₁₂ to about C₂₀ in the hydrocarbon portionthereof and R′ is lower alkyl ranging from about C₁ to C₃.
 3. Theinhibitor of claim 1 wherein the isoalkane is a mixture of C₆ to C₂₀petroleum distillate.
 4. A lubricant comprising: (a) a major amount ofmineral oil and (b) the inhibitor of claim
 1. 5. The lubricant of claim4 wherein each of the components is a food grade component.
 6. Thelubricant of claim 5 wherein the mineral oil is white oil.
 7. Thelubricant of claim 6 which comprises, by volume, based on the totalvolume, (a) from about 80% to about 99% of the mineral oil, and (b) fromabout 1% to about 20% of the additive.